68 n will mean that it's capacity is 68 nano farads. (= 0.068 uF) 250 v AC is it's working voltage. X2 is a rating to say that it is suitable to be used connected directly across the mains. 335 is just the type and packaging. I suspect the capacitor will be connected either directly across the brushes or directly across the mains. It will be to suppress electrical interference. It is very unlikely it is required for the device to function. (I am assuming the motor is a series wound type.
Thanks for the reply Les. The capacitor is connected across the mains.
Even if not faulty this is still useful information, thankyou. I will continue to dig a bit deeper. Even if I never get the appliance working again it's no great loss, more something to tinker with, but would be good for my own satisfaction!
As Les said, it's almost certainly not the problem - and not something I (or any other service engineer) would even look at (if it was faulty it would normally be blown to pieces, and instantly obvious). But as it's not a functional component, then even if blown to pieces it wouldn't stop the unit working.
Common problems would usually be the motor, or the speed controller - speed controllers make life difficult, because they are difficult to test - and also are often destroyed by the motor failing.
Thanks for the replies everyone. Disassembled the motor a couple of evening ago, tested what I could and in the end only cleaned brushes and commutator. Now up and running again!
Thanks for the replies everyone. Disassembled the motor a couple of evening ago, tested what I could and in the end only cleaned brushes and commutator. Now up and running again!